Dual metal contacts are described in Mancini, U.S. Pat. No. 3,317,888, issued May 2, 1967, and in Berg, U.S. Pat. No. 3,370,265, issued Feb. 20, 1968. The aforementioned patent describes a dual or bi-metallic circuit board pin comprising a base and a spring metal contact leaf. The contact leaf is fixedly mounted to the base at one end and retained by a hook on the base at the other end. The latter mentioned patent describes a contact comprising a socket and a bowed contact spring. The contact spring is confined in the socket but is free to move relative to the socket. In both of these contacts, the base or socket can be made of a malleable metal of high electrical conductivity such as brass, copper or phosphor bronze, and the spring can be made of a resilient spring metal such as spring steel, beryllium copper or other spring metals or alloys. Both the base or support and the spring can be plated or coated with a corrosion resistant layer such as gold or tin-lead, to assure a good electrical contact between the contact and a mating contact. In both of the above contacts the spring is bowed and, upon engagement with a mating contact, the spring is deflected and flattened at its midpoint to provide a flat area of contact between the spring and mating contact with a force proportional to the deflection of the spring. A plug jack connector is described in Klassen, U.S. Pat. No. 3,273,105, issued Sept. 13, 1966. The connector includes a contact having two spaced bends on both sides of its midpoint.
An electrical connector having a contact comprising a support and an arcuately stressed plate spring having each end fixedly mounted to the support where the spring is adapted to deflect and flex at its midpoint during engagement by a mating contact is described in Ser. No. 755,128, filed Dec. 28, 1976 to B. Mouissie (U.S. Pat. No. 4,109,986). During the operation of the above-described connector, the spring surfaces on both sides of the spring's midpoint provide the contact surfaces with a mating contact. Potential disadvantages arise from the difficulty in obtaining springs having both the necessary malleability and conducting properties or, if plated, in maintaining good electrical contact between spring and mating contact and from the increased contact resistance resulting from repeated insertions and removals of the mating contact damaging the surface plating.